subquery

Ichki so‘rov — boshqa so‘rov ichidagi SELECT. Natijasi qiymat, ro‘yxat yoki jadval bo‘lishi mumkin.

-- o‘rtachadan yuqori maosh
SELECT name, salary FROM employees
WHERE salary > (SELECT AVG(salary) FROM employees);

-- buyurtma bergan mijozlar
SELECT name FROM customers
WHERE id IN (SELECT customer_id FROM orders);

-- har bo‘lim rekordchisi (bog‘liq ichki so‘rov)
SELECT name, department_id, salary FROM employees e
WHERE salary = (SELECT MAX(salary) FROM employees WHERE department_id = e.department_id);

Ko‘p qadamli so‘rovlarni WITH (CTE) bilan o‘qilishi oson qilib yozing:

WITH totals AS (SELECT customer_id, SUM(amount) AS s FROM orders GROUP BY customer_id)
SELECT * FROM totals WHERE s > 100000;